'Digging up all the Details' - Somerset Regional Council · Geotechnical Soils Pty Ltd ABN: 15 895...

'Digging up all the Details'

ABN: 15 895 975 485

Geotechnical Soils

Soil Investigation Summary

Client PLATINUM AUSTRALIA

Site Address Lot 157, SP 264094, Corella Street, Eagle Rise Estate, Lowood

4311Job No SI 1616

Date 23/11/2019

Test Method: Vehicle Mounted Rig

Wind Category: N3

Site Details:

Vegetation Medium/ long plated grasses.

Drainage Poor, ponding likely. Generally, runoff will disperse to the frontage (east). No

inter-allotment drainage network.

Geology Gatton Sandstone unit that consists of fine - medium grained, feldspathic/

lithic sandstone within a clay/ pebbly matrix. Lower on the flank there are

depositional deposits described as Stranded River Terrace alluvium.

Soil Profile Three boreholes (BH) advanced at representative locations (no building siting

supplied) by a small vehicle mounted drilling rig. Test locations shown on

PLATE 1 and subsoil profiles in APPENDIX A.

Boreholes revealed estate filling of -:

- BH 1 - 0.1/0.55m (topsoil and estate fill)

- BH 2 - 0.2m (topsoil)

- BH 3 - 0.15m (topsoil)

(Informative AS 4055)Attachments: Site Plan/ Subsoil Profiles/ Photographs

Purpose Proposed Residence

Reference Documents

[email protected]

Office: 0413 951 99114/40 Claude Boyd Parade

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Bells Creek QLD 4551

- Morrison Geotechnic - Level One Compliance Report for Earthworks Fill - Eagle

Rise Stages 4/44 job no. DL 14/268 and ref no 9325 dated 15th December 2014

Description Allotment 807m² in area and rectangular in shape. Allotment is located over a

broad hillside that has allotments terraced into the flank. The terracing on the

allotment has been created by significant dry boulder walls inside and outside

the southern and northern boundaries, respectively. The upslope (southern)

boulder wall is 2.1 metres in height and 1.5 metres inside the property

boundary. The wall tapers to ground level across the rear boundary. The

downslope (northern) boulder wall is 1.1/2.1 metres in height and 3.2 metres

outside the property boundary. Please note, we have not received or able to

source an engineering certification of the boulder walls. Any estate filling is

certified to Level 1 (AS 3798) in the referenced documentations. No building

siting or type supplied, however it is anticipated the future residence will be

within the front lot half and supported by slab-on-ground and/or suspended

timber floor. Two sewer manholes across the frontage. Photographs attached.

Topography The allotment has been benched (terraced) into the flank, with 2.1 metre

boulder walls upslope (south) and downslope (north). The allotment frontage,

transitions from 1.3 metre above the benched area, to on-grade centrally and

1.0 metres above the northeastern footpath. The benched area has a slight

fall of 0.15 metres to the south/ southeast.

Date 23/11/2019

Job No SI 1616Site Address Lot 157, SP 264094, Corella Street, Eagle Rise Estate, Lowood

4311



Dynamic cone penetrometer tests (DCP) confirmed moderate/ good, estate

fill consistencies. The residual (weathered in-place) clays are (CL/CH) and of

good consistencies.

A fine-coarse granular SANDSTONE rock at depths of -:

- BH 1 - 1.35m

- BH 2 - 1.55m

- BH 3 - 0.15m (rock/clay)

Discussion / Remarks

The following comments are in the context of no know building siting or

construction type.

(AS 2870-2011)

Estimated Cut N/A

Estimated Fill N/A

Removal of Trees No

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- long grasses and topsoils to be stripped from the building envelope - engineering certification of massive boulder retaining walls

- sheer angle of 450 to construction adjacent a step-down wall

or excavation i.e. northern side boundary

- some (CH) silty CLAYS that are moderately/ highly reactive

- depths to weak rock (0.15/1.55m)

- poorly drained

- due to the presence of (CH) clays, refer to APPENDIX 'CH/H' - Guide to

Design of Footings For Trees

- the allotment is primarily in cut with localised 'estate' filling to the northeastern corner that is certified to Level 1 (AS 3798).

Laboratory Data: Database values for the (CH) silty CLAYS are -:

- Liquid Limit 56%

- Plasticity Index 42%

- Linear Shrinkage 18.0%

- Estimated Instability Index 4.1%

Site Scrape Only Yes

Piers To Rock

The rock is of good ripperbility with boreholes advanced 0.55/ 1.8 metres

into the rock matrix. Clay lenses within the rock layers.

Building founding considerations include-:

Site Classification: In accordance with AS 2870, 2.5.3 (a)(ii)the site is classified 'P'(controlled deep

fill). However, based on clay reactivity the characteristic surface movement (Ys) calculates to range 40 - 45mm or H1.

Geotechnical Soils Pty Ltd

ABN: 15 895 975 485

Sunshine Coast, Queensland

Office: 0413 951 991

[email protected]

www.geotechnicalsoils.com.au

APPENDIX ASub Soil Profiles

Date 23/11/2019


4311



0.1 1

0.2 6

0.3 8

0.4 7

0.5 7

0.6 9

0.7 6

0.8 8

0.9 9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

Test Values Location 7m FRONT BOUNDARY 3m RH (NORTHERN) SIDE BOUNDARY

Test No. 1

(per 100mm)

Procedure:AS 1289.6.3.2/3-1997

Depth Description Symbol CommentsOrigin (Unified Classification)

100 Sandy CLAY low plasticity, dark brown, fine sands, with silt, moist, soft.

CLFill

650 Gravely CLAY medium plasticity, yellow/ yellow brown, fine-medium gravel, with fine-coarse sand, moist, stiff/very stiff.

CLFill

1350 Silty CLAY high plasticity, light yellow/ light orange yellow/ light grey, some fine sand, slightly moist/moist, very stiff.

CH

2400 ROCK - SANDSTONE extremely weathered, yellow brown, lenses of (CL) sandy CLAYS, dry/slightly moist, very low strength.

XW END

0.1 1

0.2 8

0.3 8

0.4 3

0.5 4

0.6 5

0.7 5

0.8 7

0.9 7

1.0 9

1.1 11

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

Test Values Location 23m FRONT BOUNDARY 10m LH (SOUTHERN) TOE OF BOULDER WALL

Test No. 2

(per 100mm)

Procedure:AS 1289.6.3.2/3-1997


200 Sandy CLAY low plasticity, dark brown, fine sands, with silt, moist, soft/firm.

CLFill

450 Sandy CLAY high plasticity, yellow brown/ orange yellow brown, fine-medium sands, with silt, moist, stiff/very stiff.

CH

1100 Sandy CLAY medium plasticity, yellow brown/ grey mottle, fine-medium sands, with silt, moist, very stiff/hard.

CL

1550 Silty CLAY high plasticity, light grey/ light grey yellow / yellow brown, some fine sand, slightly moist, hard.

CH

2100 ROCK - SANDSTONE extremely weathered, light grey/ light grey yellow, lenses of (CL) sandy CLAYS, dry, very low strength.

XW REFUSAL ON ROCK

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Date 23/11/2019


4311



0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

3.9

4.0

Test Values Location 11m FRONT BOUNDARY 4m LH (SOUTHERN) TOE OF BOULDER WALL

Test No. 3

(per 100mm)

Procedure:AS 1289.6.3.2/3-1997


150 Sandy CLAY low plasticity, dark brown, fine sands, with silt, moist, soft/firm.

CLFill

1000 ROCK - SANDSTONE extremely weathered, yellow brown, interbedded with (CH) sandy CLAY, slightly moist/moist, very low strength.

CH/XW

1800 ROCK - CARBONACEOUS SHALE extremely weathered, light grey, slightly moist/moist, low strength.

XW END

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Interpretations, Terms and Symbols

Limitations

1. This document is supplied to a specific person for a specific purpose with the scope of review defined by the client’s requests and with reference to the relevant industry standards.

2. The details within this report are based on site and soil conditions encountered at that time.

3. Assessment methods and procedures are in accordance with the referenced standards.

4. The soil profiles presented represent that actual location and can be extrapolated to render an opinion on overall subsurface conditions within a defined area.

5. The transition between soil types and layers in both vertical and horizontal dimensions can be more gradual or abrupt than this document indicates and over time, manmade or natural events may alter the site conditions.

6. External documentation referenced which can be included: fill certification, soil profiles, laboratory test results and consolidation parameters are included with an acknowledgement and understanding that the conclusions are the responsibility of that documents author.

Review Procedures

AS 1289 Methods of Testing of Soils for Engineering Purposes

AS 1726 Geotechnical Site Investigations

AS 2870 Residential Slabs and Footings – Constructions

AS 3798 Guidelines on Earthworks for Commercial and Residential Development

AS 4055 Wind Loads for Housing

The following glossary of terms used in the description of the prevailing soil conditions is compliant with Unified Classification System with soil profile depths recorded as the END depth of that soil type.

D depth of that soil type. Soil Descriptions

Description and Classification of Soils for Geotechnical Purposes: Refer to AS1726-1993 (Appendix A).

The following chart (adapted from AS1726-1993, Appendix A, Table A1) is based on the Unified Soil Classification System (USCS).

Soil Colour: Is described in the moist condition using black, white, grey, red, brown, orange, yellow, green or blue. Borderline cases can be described

as a combination of two colours, with the weaker followed by the stronger. Modifiers such as pale, dark or mottled, can be used as necessary. Where

colour consists of a primary colour with secondary mottling, it should be described as follows:

(Primary) mottled (Secondary). Refer to AS 1726-1993, A2.4 and A3.3.

Soil Moisture Condition: Is based on the appearance and feel of soil. Refer to AS 1726-1993, A2.5.

Major Divisions

Particle size mm

USCS

Group

Symbol

Typical Names

Laboratory Classification

CO

AR

SE

GR

AIN

ED

SO

ILS

(m

ore

tha

n h

alf

of m

ate

rial l

ess

than

63

mm

is la

rge

r th

an

0.0

75m

m)

BOULDERS

COBBLES

GRAVELS

(more than

half of coarse

fraction is

larger than

2.36 mm)

SANDS

(more than

half of coarse fraction is

smaller than 2.36 mm)

200

63

coarse

20

medium

6

fine

2.36

coarse

0.6

medium

0.2

fine 0.075

% < 0.075 mm

(2) Plasticity of fine fraction

Cu= D60

D10

Cc = (D 30)2

(D10)(D60)

NOTES

GW

Well graded gravels and gravel-sand mixtures, little or

no fines

U

se t

he g

rad

atio

n c

urv

e o

f m

ate

rial p

ass

ing

63 m

m fo

r cl

ass

ifica

tion

of f

ract

ions

acc

ord

ing

to th

e c

riter

ia g

iven

in 'M

ajo

r D

ivis

ions

'

0-5

>4

Between 1 and 3

(1) Identify fines by

the method given for fine-grained

soils.

(2) Borderline classifications

occur when the percentage of fines (fraction smaller than 0.075 mm size) is greater than

5% and less than12%. Borderline classifications require the use

of SP-SM, GWGC.

GP

Poorly graded gravels and gravel-sand mixtures, little or

no fines, uniform gravels

0-5

Fails to comply with

above

GM Silty gravels, gravel-sand-silt

mixtures (1) 12-50

Below 'A'line or PI<4

GC

Clayey gravels, gravel-sand clay mixtures (1)

12-50

Above 'A' line and

PI>7

SW

Well graded sands andgravelly sands, little or no

fines

0-5

>6

Between 1 and 3

SP

Poorly graded sands andgravelly sands, little or no

fines

0-5

Fails to comply with above

SM

Silty sands, sand silt mixtures(1)

12-50

Below 'A' line or PI<4

SC

Clayey sands, sand-clay mixtures (1)

12-50

Above 'A' lineand

PI>7

FIN

E G

RA

INE

D S

OIL

S

(mor

e th

an

ha

lf of

mat

eria

l les

s th

an 6

3 m

m is

sm

alle

r th

an 0

.07

5 m

m)

SILTS & CLAYS

(Liquid Limit ≤50%)

ML

Inorganic silts, very fine sands, rock flour, silty or

clayey fine sands or clayey silts with slight plasticity

CL CI

Inorganic clays of low to medium plasticity, gravelly

clays, sandy clays, silty clays, lean clays

OL

Organic silts and clays of low plasticity

SILTS & CLAYS

(Liquid Limit >50%)

MH

Inorganic silts, mic- aceous or diato-maceous fine sands

or silts, elastic silts

CH

Inorganic clays of high plasticity, fat clays

OH

Organic silts and clays of high plasticity

HIGHLY ORGANIC SOILS

PT

Peat and other highly organic soils

Soil Particle Sizes

Term

Size Range

BOULDERS

COBBLES

Coarse GRAVEL

Medium GRAVEL

Fine GRAVEL

Coarse SAND

Medium SAND

Fine SAND

SILT

CLAY

>200 mm

63-200 mm

20-63 mm

6-20 mm

2.36-6 mm

0.6-2.36 mm

0.2-0.6 mm

0.075-0.2 mm

0.002-0.075 mm <0.002 mm

Term Description

Dry

Cohesive soils; hard and friable or powdery, well dry of plastic limit.

Granular soils; cohesionless and free-running

Moist

Soil feels cool, darkened in colour.

Cohesive soils can be moulded.

Granular soils tend to cohere.

Wet

Soil feels cool, darkened in colour.

Cohesive soils usually weakened and free water forms on hands when handling.

Granular soils tend to cohere and free water forms on hands when handling.

Consistency of Cohesive Soils: May be estimated using simple field tests, or described in terms of a strength scale. In the field, the undrained shear

strength (su) can be assessed using a simple field tool appropriate for cohesive soils, in conjunction with the relevant calibration. Refer to AS 1726-1993,

Table A4.

Note: SPT - N to qu correlation from Terzaghi and Peck, 1967. (General guide only).

Consistency of Non-Cohesive Soils: Is described in terms of the density index, as defined in AS 1289.0-2000. This can be assessed using a field tool

appropriate for non-cohesive soils, in conjunction with the relevant calibration. Refer to AS 1726-1993, Table A5; BS5930-1999, p117.

Consistency - Essentially Non-Cohesive Soils

Term Symbol SPT N Value Field Guide Density Index (%)

Very loose VL 0-4 Foot imprints readily 0-15

Loose L 4-10 Shovels Easily 15-35

Medium dense MD 10-30 Shovelling difficult 35-65

Dense D 30-50 Pick required 65-85

Very dense VD >50 Picking difficult 85-100

Standard Penetration Test (SPT): Refer to. AS 1289.6.3.1-2004. Example report formats for SPT results are shown below:

Test Report Penetration Resistance (N) Explanation / Comment

4, 7, 11 N=18 Full penetration; N is reported on engineering borehole log

18, 27, 32 N=59 Full penetration; N is reported on engineering borehole log

4, 18, 30/15 mm N is not reported 30 blows causes less than 100 mm penetration (3rd interval) – test discontinued

30/80 mm N is not reported 30 blows causes less than 100 mm penetration (1st interval) – test discontinued

rw N<1 Rod weight only causes full penetration

hw N<1 Hammer and rod weight only causes full penetration

hb N is not reported Hammer bouncing for 5 consecutive blows with no measurable penetration – test discontinued

Consistency - Essentially Cohesive Soils

Term

Field Guide

Symbol

SPT

“N”

Value

Undrained

Shear Strength su (kPa)

Unconfined Compressive

Strength qu (kPa)

Very soft

Oozes between fingers when squeezed in hand.

VS

0-2

<12

<25

Soft

Easily moulded with fingers.

S

2-4

12-25

25-50

Firm

Can be moulded by strong pressure of fingers.

F

4-8

25-50

50-100

Stiff Not possible to mould with fingers.

St 8-15 50-100 100-200

Very stiff VSt 15-30 100-200 200-400

Hard

Can be indented with difficulty by thumb nail.

H

>30

>200

>400

Rock Descriptions

Refer to AS 1726-1993 (Appendix A3.3) for the description and classification of rock material composition, including:

(a) Rock type (Table A6, (a) and (b))

(b) Grain size

(c) Texture and fabric

(d) Colour (describe as per soil).

The condition of a rock material refers to its weathering characteristics, strength characteristics and rock mass properties. Refer to AS 17261993

(Appendix A3 Tables A8, A9 and A10).

Weathering Condition (Degree of Weathering):

The degree of weathering is a continuum from fresh rock to soil. Boundaries between weathering grades may be abrupt or gradational.

Rock Material Weathering Classification

Weathering Grade Symbol Definition

Residual Soil

RS Soil-like material developed on extremely weathered rock; the mass structure and substance fabric are no longer evident; there is a large change in volume but the material has not been significantly transported.

Extremely Weathered Rock

XW

Rock is weathered to such an extent that it has 'soil' properties, i.e. it either disintegrates or can be remoulded in water, but substance fabric and rock structure still recognisable.

Highly Weathered Rock

HW

Strong discolouration is evident throughout the rock mass, often with significant change in the constituent minerals. The intact rock strength is generally much weaker than that of the fresh rock.

Moderately Weathered Rock

MW

Modest discolouration is evident throughout the rock fabric, often with some change in the constituent minerals. The intact rock strength is usually noticeably weaker than that of the fresh rock.

Slightly Weathered Rock SW Rock is slightly discoloured but shows little or no change of strength from fresh rock.

Fresh Rock FR Rock shows no sign of decomposition or staining.

Notes:

1. Minor variations within broader weathering grade zones will be noted on the engineering borehole logs.

2. Extremely weathered rock is described in terms of soil engineering properties.

3. Weathering may be pervasive throughout the rock mass, or may penetrate inwards from discontinuities to some extent.

4. The ‘Distinctly Weathered (DW)’ class as defined in AS 1726-1993 is divided to incorporate HW and MW in the above table. The symbol DW should not be used.

Strength Condition (Intact Rock Strength):

Strength of Rock Material

(Based on Point Load Strength Index, corrected to 50 mm diameter – Is(50). Field guide used if no tests available. Refer to AS 4133.4.1-2007.

Term

Symbol

Point Load Index (MPa)

Is(50)

Field Guide to Strength

Extremely Low EL ≤0.03 Easily remoulded by hand to a material with soil properties.

Very Low

VL

>0.03

≤0.1 Material crumbles under firm blows with sharp end of pick; can be peeled with knife; too hard to cut a triaxial sample by hand. Pieces up to 3 cm thick can be broken by finger pressure.

Low

L

>0.1

≤0.3

Easily scored with a knife; indentations 1 mm to 3 mm show in the specimen with firm blows of the pick point; has dull sound under hammer. A piece of core 150 mm long by 50 mm diameter may be broken by hand. Sharp edges of core may be friable and break during handling.

Medium

M

>0.3

≤1.0

Readily scored with a knife; a piece of core 150 mm long by 50 mm diameter can be broken by hand with difficulty.

High

H

>1

≤3 A piece of core 150 mm long by 50 mm diameter cannot be broken by hand but can be broken by a pick with a single firm blow; rock rings under hammer.

Very High VH >3 ≤10 Hand specimen breaks with pick after more than one blow; rock rings under hammer.

Extremely High

EH

>10 Specimen requires many blows with geological pick to break through intact material; rock rings under hammer.

Notes:

1. These terms refer to the strength of the rock material and not to the strength of the rock mass which may be considerably weaker due to the effect of rock defects.

2. Anisotropy of rock material samples may affect the field assessment of strength.

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